If tossing 1 head is 1/2, then you have to do 1/2^4 which is 1/2 × 1/2 × 1/2 × 1/2 (I imagine it as a tree diagram if that helps). 2^4 is 16, so your answer is b) 1/16. Hope this helps!
I do not know English :33333
Put a dot on the 4 on the y line. then from that point go down 3 and to the right 4.